This new R01 application is submitted in response to PA-08-192 Geographic and Contextual Influences on Energy Balance-Related Health Behaviors. The project proposes multilevel, longitudinal evaluation of obesity related contexts and resulting outcomes (i.e., obesity related behaviors) and impacts (i.e., obesity related endpoints) using the National Health and Nutrition Examination Study (NHANES). The National Center for Health Statistics has recently made available for analysis the georeferenced NHANES to approved researchers. As approved research, the project is organized around characterizing the various food and physical activity environments at the neighborhood and community levels for Continuous NHANES participants in the five surveys conducted and available since 1999 (i.e., NHANES 1999-2000, 2001-2002, 2003-2004, 2005-2006, 2007-2008). By locating NHANES survey respondents within their respective neighborhoods (e.g., census tracts) and political jurisdictions (e.g., census place) and characterizing these locations in terms of the food and physical activity environments the many strengths of the NHANES can be brought to bear to evaluate a number of outstanding issues in the obesity literature. PUBLIC HEALTH RELEVANCE: Despite growing awareness of the negative health impact of poor diet, physical inactivity and excess weight, obesity prevalence has increased to epidemic levels in the United States. The consensus among public health experts is that individual changes are not responsible for the rapid rise in obesity and the explanation must lie in the broader societal effects resulting from environmental changes evidenced in American neighborhoods and communities. The proposed project will bring to bear the most comprehensive national survey of diet and physical activity in the United States, the National Health and Nutrition Examination Survey (NHANES), for studying the epidemic by using the recently available geographic locations of NHANES participants to characterize their neighborhood and community food and physical activity environments.